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Pv DANCKWARDT.

PRocEss FOR PRODUCING ANHYDRous ALUMINUM cHLoRID.

APPLICATION FILED )UNE 23, 1919.

1,343,662. Patented Jun@ 15, 192m wav-r UNITED STATES PATENT OFFICE.

PAUL DANQKWARDT, OF DENVER, COLORADO.

PROCESS FOR PRODUCING ANHYDROUS ALUMINUM CHLORID.

Application mea June 23,

To all whom it may concern:

Be it known that I, PAUL DANoKwARur, a citizen of the United States, residing 1n the city and county of Denver and State of Colorado, have invented certain new and useful Improvements in Processes for Producing Anhydrous Aluminum Chlorid; and I do declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompany ing drawings, and to the characters of reference marked thereon, which form a part of this specication.

This invention relates specifically to a process for producing aluminum chlorid by electrolysis of a molten metal chlorid, while a mixture of substances containing an aluminum compound is in contact with the posi tive pole, or is itself forming the positive pole, the current in decomposing the metal chlorid, causing metal to be separated at the negative pole and chlorin at the positive pole. The metal is withdrawn at intervals; the chlorin reacts with the aluminum of the aluminum compound in the vicinity of the positive pole, forming anh drous chlorid, which volatilizes and is con ensed in a suitable chamber. This part of the process takes place at an elevated temperature in that part of the apparatus where electrolysis is taking place.

As a raw material for the supply of the aluminum compound, I may utilize the cake or residue obtained in the process of treating mineral oils with anhydrous aluminum chlorid, as carried out in making gasolene from such oils. This residue at present is a waste product and practically of no value, as the aluminum chlorid contained therein has become ineffective. Or, I may use a mixture of aluminum oXid and carbon. The aluminum oXid may be that obtained as a by-product in a certain process for producing zinc chlorid from the residue above described. As an electrolyte, I prefer to usev zinc chlorid, although other chlorids may be used, for instance, lead or copper chlorids.

The chief object of this invention is to utilize the ineffective aluminum chlorid in the residue above `described directly, and thereby regenerate it, and also to provide a use for the aluminum oXid and zinc chlorid produced as above mentioned.

In the accompanying drawing:

Figure 1 is a vertical section through one Specification of Letters Patent.

Patented June 15, 1920.

1919. Serial No. 306,181.

form of apparatus in which the process may be carried on.

F ig. 2 is a horizontal section, taken on the line 2-2 of Fig. 1.

The apparatus comprises an electrolyzer composed of two sections having steel shells, 1 and 2, with their iianges 3 bolted together and insulated by asbestos layers 4. The two shells 1 and 2 are provided with an inside lining of fire brick 5, which is projected downward and rests upon the inclined bottom fire brick lining (i, and has a number of openings 7 in the lower part thereof to offer free communication between the two compartments A and B, as shown. At the extreme left of the compartment A, an opening 8 through the wall serves as a tap-pole for drawing off the molten contents. A pipe 9, projecting down into compartment A, enters the molten bath when the apparatus is filled, and serves for the introduction of fresh material. This pipe 9 should be made of non-conducting and heat-resisting material.

The compartment B is provided with a door 10 for the removal of charge, and a charging duct 12, with cap 14, is provided for the introduction of charge.

The negative electrode 15 is formed bya strip of iron bolted to the steel shell and projecting therethrough to form a communication between a layer of molten zinc inside the apparatus and the current supplying means outside. A carbon rod 16, forming the positive pole, passes through the top of compartment B, its outer end being connected with the current.

A conduit 17 connects compartment B of the electrolyzer with a condensing chamber 18, which is built of brick and provided with a smooth surface on the inside, preferably glazed bricks, from which the solid, condensed salt may be easily detached for removal through the door 19. Any material not condensed is sucked off through the pipe 20, to a steam exhaust 21, by means of which it is forced through the perforated extension 22 of the pipe 28, which extends down into the lower portion of the absorber 24, the latter, when in operation, being filled with water holding zinc oXid in suspension. The latter is for the purpose of collecting any hydrochloric acid or free chlorin escapingI from the condenser 18. The absorber 24 consists of a lead-lined, iron or wooden tank, and has an outlet 25 for waste gases.

In carrying on the process with this apparatus, the absorber 2li is filled with Water and zinc oXid, as stated. A mixture containing aluminum compound is then introduced through the duct l2 into the chamber B. The amount `of carbon in this material should be such that it is at least sufficient to take up all the oxygen of the aluminum oXid, forming carbon monoXid. The residue before mentioned contains hydrocarbons and carbon sufficient for this purpose, while if aluminum oxidis used,carbon must be added in proper proportions.

Melted zinc chlorid, or other electrolyte, is then introduced through the pipe 9 in sufficient quantity to fill up to the line 2-2 of Fig. l. rlhe current is then turned on immediately. As the current finds the greatest resistance in passing from the carbon electrode through the mixture containing the aluminum compound, it is here that the most heat is produced. Therefore it is advisable in the beginning not to let the carbon pole itself dip into the molten electrolyte, as the Zinc chlorid is a very good conductor of electricity and otherwise there would not be suficient current transformed into heat to bring the charge up to the required temperature. lVhen the charge becomes red hot, a large amount of gas is evolved, consisting` principally of carbon monoxid and hydrochloric acid, with some hydrocarbons, if the above-described residue is used, and almost entirely of carbon monoxid With a little chlorin if carbon and aluminum oXid are'used. As the charge becomes hotter and the electrolysis of the zinc chlorid increases, copious fumes of anhydrous aluminum chlorid are generated. The gases and vapors not condensed in condenser 18 are forced through the Water containing` thevzinc oxidin suspension-in the absorber 2a. Thezinc set free at the bottom of the electrolyzer is'drawn off through the outlet if a mixture of aluminum oxid and carbon is used. If the above-described residue is used, the reaction is more complica-ted and Vmay be expressed by some such equation as This latter equation is hypothetical, but it expresses the fact that a certain amount of free hydrochloric acid is liberated.

The aluminum chlorid condenses in the condensing chamber' 18 from which it is removed through the door 19, whenever a sulicient amount has accumulated. rPhe eX- haust 2l is operated at such a rate that no aluminum chlorid, but all of the gases, are carried over and forced through the emulsion of zinc oXid. Zinc chlorid will be yformed by the reaction of the hydrochloric acid With the zinc oXid, and when the solution becomes saturated with Zinc chlorid, it may be filtered, the filtrate evaporated, and the residue of zinc chlorid melted down and used in the process as a part of thc electrolyte.

The aluminum chlorid thus produced is not pure, as it invariably contains some Zinc chlorid volatilized along with the aluminum chlorid. This contamination, however, is not objectionable when the aluminum chlorid is to be used for making gasolene. However, it may be freed of the zinc chlorid by resubliming in a retort iired from the outside, the Zinc chlorid remaining behind.

I claim:

l. A process of producing anhydrous aluminum chlorid which consists in electrolyzing a metal chlorid in contact With an aluminum compound so that the chlorin 1n nascent state can react vvith it, forming anhydrous aluminum chlorid.

2. The process of producing anhydrous aluminum chlorid, which consists in electrolyzing molten metal chlorid while the positive pole is in contact with a charge conv taining carbon and an aluminum compound, allowing the chlorin from the chlorid to react with the charge to form an aluminum chlorid, and condensing the vapors of aluminum chlorid so formed.

3. The process of producing anhydrous aluminum chlorid, which consists in electrolyzing molten metal chlorid, using a mixture of carbon and an aluminum compound at the positive pole at such temperature that the aluminum chlorid formed volatilizes, and condensing the latter.

a. The process of producing anhydrous aluminum chlorid, which consists in electrolyzing molten zinc chlorid in contact with carbon and an aluminum compound at the positive pole, causing the liberated chlorin to react with the charge to form anhydrous aluminum chlorid, maintaining the temperature suflicient to volatilize the anhydrous aluminum chlorid formed, and condensing` the latter.

5. The process of producing anhydrous aluminum chlorid, which consists in electrolyzing molten zinc chlorid, thereby scparating it into metallic zinc and chloriu. causing the latter in nascent state to react with aluminum oxid and carbon to form aluminum chlorid, and condensing the volatilized aluminum chlorid.

In testimony whereof I atlix my signature.

PAUL DANCKVAR DT. 

